##
## uniquefield.py
## Login : <uli@pu.smp.net>
## Started on  Sat May 28 13:39:15 2011 Uli Fouquet
## $Id$
## 
## Copyright (C) 2011 Uli Fouquet
## This program is free software; you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 2 of the License, or
## (at your option) any later version.
## 
## This program is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
## GNU General Public License for more details.
## 
## You should have received a copy of the GNU General Public License
## along with this program; if not, write to the Free Software
## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
##
"""
Unique field indexes.
"""
from grok.index import IndexDefinition
from zope.catalog.field import FieldIndex
from zope.index.field import FieldIndex as RawFieldIndex
from zope.interface import implements
from waeup.sirp.index.interfaces import IUniqueFieldIndex, IUnique

class RawUniqueFieldIndex(RawFieldIndex):
    """Unique field index.
    """
    implements(IUnique)

    def index_doc(self, docid, value):
        """Index some doc.
        """
        entries = self._fwd_index.get(value, ())
        if len(entries) > 0 and docid not in entries:
            # Accept already existing entries if docid matches
            # ('reindex' use case). If docid is not contained already,
            # we have a unique-constraint violation.
            raise KeyError(
                'The value already exists in catalog: %s' % value,)
        return super(RawUniqueFieldIndex, self).index_doc(docid, value)

class UniqueFieldIndex(FieldIndex):
    implements(IUniqueFieldIndex)

class UniqueField(IndexDefinition):
    """A :class:`grok.Indexes` index that matches against an entire field.

    Contrary to :class:`grok.index.Field` this index only accepts
    unique values.
    """
    index_class = UniqueFieldIndex